For a variety of reasons, it is desirable to supply fluids such as electrolytes or to or collect fluids from a patient in various settings including hospitals, nursing homes, private homes, or wheelchairs. For example, there are many instances of patient treatment where it is necessary to collect and determine, at all times, the accurate amount of expelled body fluids, such as urine, that is being passed or released by the patient. It is, in fact, conventional in hospitals to collect urine from certain patients to measure and monitor urine output. This is routinely done for post-operative patients as well as those with urologic disorders where, for example, urine output is directly related to renal function. This type of procedure for collecting, measuring and monitoring urine takes on extreme importance because, for example, sudden changes in urine flow, which can occur at any time, can indicate that there is a deteriorating clinical condition in the patient. Changes in urine output have been correlated with changes in cardiac output.
The invasive collection of urine and measurement of urine output are typically accomplished by first catheterizing the patient, i.e. a catheter is passed through the urethra of the patient into the bladder. The other end of the catheter is connected to a container or vinyl drainage bag through a length of flexible tubing attached to an inlet-barbed fluid port of the bag. Typically the bag is supported below the patient from the patient's bed or other support system such as a wheelchair, and urine drains by gravity from the patient through the flexible tubing and into the collection bag. For those patients who are mobile, this collection device or bag is called a leg bag, and those in a hospital bed would have what is called a bed bag. Bed bags are usually 2,000 ml in capacity and leg bags are 1,000 ml, 800 ml, 700 ml, or even smaller. In addition to monitoring urine output as a function of time, the reservoir of a collection bag fills to capacity at unpredicted intervals and someone must empty the bag so it can fill once again with urine. Patients can sometimes obstruct the flow of urine into the bag by lying on the drain tube. Further, if there is blood in the urine, blood clots can form that may obstruct the catheter. In these cases, no urine appears in the bag after an expected time period. Both a filled bag and blocked tube can cause urine backup and a backup could cause deleterious effect on the patient's condition. For all the above reasons, monitoring collection bags is an important part of providing effective patient therapy.
Prior art describes different types of systems that are employed to collect and measure urine output. For example, several systems use urine collection bags formed of a clear and flexible plastic (vinyl) material, which contain indicia in the form of graduations on the bag itself that represents the volume of the urine in the bag. In other systems the urine collection receptacle includes a rigid and clear plastic reservoir in fluid communication with a collection bag, which reservoir has volume related indicia and into which the urine initially flows and is stored prior to being emptied into the bag. See, for example, the urine meter bag described in U.S. Pat. No. 4,305,405.
These devices present several disadvantages. For example, there is a lack of accuracy in obtaining measurement readings that are made using the printed indicia and there is often a degree of difficulty in reading these devices depending on where they are positioned. Furthermore, the urinary output measurements and bag fill monitoring are dependent upon a person coming at precise time intervals to personally obtain and record bag fill data. This is often difficult to do. If the patient's room is dark a light must be turned on, disturbing the patient, and also disturbing their roommate in a double room.
There are several types of mechanical, electromechanical, and electronic devices used for metering, weighing and otherwise automatically monitoring and/or collecting body fluids, such as urine. Aside from the fact that many of these devices lack a certain degree of accuracy, they often present problems dealing with safety, high cost to manufacture and/or to operate, lack of portability and general difficulty of use. Many of these systems are often rendered inaccurate due to the influence of patient movement on the measuring or weighing device used within the system. This is particularly true because the patient is generally connected to the measuring or weighing device by flexible tubing, as seen, for example, in the systems described in U.S. Pat. Nos. 4,343,316; 4,390,073; 4,417,585; and 4,448,207.
It is also known in the art that medical offices having a fixed location and operational base can use ultrasound to measure the height of a column of urine in a rigid walled container and from that height measurement, the volume and volume flow rate of the urine is monitored. Urology doctors at their clinically controlled facilities gather controlled patient outputs to do incontinence assessments. These professional systems cost several thousands of dollars. Patients are typically scheduled for an office visit, and then a procedure is done for a medically controlled measurement and assessment of that patient's bladder and related urine production patterns.